(Auteur) Existing virtual globes, including both unique platforms and associated visualization applications, often present geospatial information with a single-view mode that restricts the user to a single dataset. Due to the absence of the functionality and user interface for coordinating multiple virtual-globe views, it is either hard or impossible to explore multiple different geospatial datasets simultaneously only using the existing virtual globes, especially when the datasets come in multiple sources, multiple spatial resolutions or multiple temporal scales. Here we present a general visualization framework that supports the exploration and comparison of various datasets with multiple coordinated views in the web-based virtual globe environment. This framework not only comprehensively considers the dynamic master/slave relationship between multiple virtual globes, but also effectively handles the coordination mechanism for diverse views to respond to users’ manipulations. We also implement a prototype application (termed MultiGlobe) and demonstrate its effectiveness over three typical application scenarios. The first case addresses the comparison of diverse imagery layers derived from different providers. A second case is examining multiple digital maps for a specific region or theme, such as time-varying LUCC datasets. As a final example, we compare and evaluate the accuracy of multiple DEMs generated from diverse data sources with different resolutions. Our informal evaluation with experts in exploratory visualization and spatial analysis confirms that the multiple-view-enhanced virtual globe can bring many benefits including focusing on spatial awareness, reducing cognitive efforts, coordinating interaction strategies, increasing browsing speed and enhancing comparison capabilities. Therefore, it can be incorporated into a variety of geospatial visualizations to replace or supplement the fixed single-view interfaces of the traditional virtual globe applications, empowering users with the ability to explore and compare multiple different datasets across the same geospatial area synchronously.

(Auteur) With the product TopPlusOpen, the Federal Agency for Cartography and Geodesy (BKG) has for the first time provided a freely accessible web map, which is based entirely on open or free data sources. For this purpose, the BKG processed and combined many different data sources in order to achieve the best possible map presentation. Among others, free official spatial data of the Federal Government and the Open Data states Berlin, Hamburg, North Rhine-Westphalia and Thuringia are presented in the product. Furthermore, Brandenburg, Mecklenburg-Western Pomerania and Rhineland-Palatinate provide their official spatial data for TopPlusOpen based on a cooperation agreement so that also these states are presented exclusively by official data. The services of the TopPlusOpen were released in September 2017. The product was very well received by the public, private and scientific sectors and is already used as a background map in many geoportals. The free access and the cross-border map presentation are especially mentioned.

(Auteur) Creating appropriate colour schemes is challenging for both novice and experienced cartographers. This paper introduces an artificial bee colony (ABC) algorithm to automatically create various colour schemes. Colour scheme creation is treated as a constrained search problem in a continuous colour space. We considered the gamut of the target device and a series of cartographic rules, such as convention, discrimination, contrast, perceptual uniformity and brightness mirror, in the ABC algorithm and presented detailed initialization, fitness definition, local exploration, and global exploration methods for creating qualitative, sequential and diverging colour schemes. The proposed method is evaluated with a case study, and the results indicate that compared with the brute force search method, the proposed method can create satisfying colour schemes of similar quality but significantly improved efficiency.

(Auteur) The cartographic representation of geographic phenomena in the space–time cube comes with special challenges and opportunities when compared with two-dimensional maps. While the added dimension allows the display of attributes that vary with time, it is difficult to display rapidly varying temporal data given the limited display height. In this study, we adapt 2D cyclic point symbols to construct 3D surfaces designed along a helical path for the space–time cube. We demonstrate how these complex 3D helical surfaces can display detailed data, including data reported daily over 100 years and data reported in four-hour intervals over a year. To create the point symbols, each value is plotted along the curve of a helix, with each turn of the helix representing one year or week, respectively. The model is modified by varying the radii from the time axis to all points using the attribute value, in these cases maximum daily temperature and four-hourly ridership, and then creating a triangulated surface from the resulting points. Using techniques common to terrain representation, we apply hue and saturation to the surface based on attribute values, and lightness based on relief shading. Multiple surfaces can be displayed in a space–time cube with a consistent time interval facing the viewer, and the surfaces or viewer perspective can be rotated to display synchronized variations. We see this method as one example of how cartographic design can refine or enhance operations in the space–time cube.

(Auteur) In recent years, immersion has become a frequently emphasized factor in the geovisualization research agenda. A principal reason for this growing interest is the assumption that immersive virtual environments (IVE) facilitate the formation of spatial presence, generally understood as the sense of “being there”. In a virtually mediated environment, the feeling of being there is of particular concern for cartographic ambitions, in terms of generating insights through geospatial representation. Current literature indicates that immersive VR systems stimulate the experience of spatial presence; however, this assumption is mainly based upon user studies in the visual communication channel. Moreover, research on IVE for geovisualization matters has to date been focused on visual-graphical rather than on auditive or even multisensory representations in virtual space. In this context, the present paper aims to evaluate the potential of audiovisual cartography with immersive virtual environments. Following a brief discussion of basic concepts, such as immersion, spatial presence and embodiment, we will integrate these aspects into a geovisualization immersion pipeline (GIP), as a framework with which to systematically link the technical and cognitive aspects of IVE. In the subsequent sections, we will examine this framework in the audio channel by analyzing how sound is implemented and perceived in GeoIVE. As we shall see, the positive effect of a combined audio-visual vs. exclusively visual presentation is supported by a series of user studies of sound effects, making audiovisual cartography with IVE a rich and worthwhile field of research.